INTRODUCTION

Placement of skeletal traction pins is a common procedure performed for temporizing management of certain fractures. Steinmann first described the distal femoral transcondylar pin in 1907, and while the evolution of the pin’s use in definitive fracture management has changed, it remains a vital tool of damage control in femoral, acetabular and vertical shear pelvic ring injuries.1,2 Furthermore, the American Board of Orthopedic Surgery (ABOS) guidelines for simulation in the postgraduate level one of residency include skeletal traction as an area of focus.3

On-call orthopedic surgery residents are often tasked with placing patients in skeletal traction often with limited experience and have been previously shown to have anxiety performing the procedure.4 There is often limited exposure to the procedure prior to performing it for the first time, often on an awake patient. While the risks associated with skeletal traction are low, they do exist. Austin et al. previously reported a 0.6% pin-site infection rate with temporary skeletal traction, including a case of septic arthritis associated with intra-articular pin placement. They also report that 17% of pins placed in their series required a second attempt due to inadequate position on the first attempt.5 Furthermore, a study conducted by Sobol et al. assessed neurovascular complications following the insertion of proximal tibial traction pins in 303 femur fracture cases. They report an incidence of 2.3% of pin-related neurological complications, with no observed vascular complications within the studied cohort.6 Although such complications are uncommon, Suri et al. reported a case of pseudoaneurysm involving the anterior tibial artery, which was attributed to excessively posterior pin insertion.7

Simulation training in orthopedics has become increasingly important, and the need for simulation models became more evident as clinical exposure was limited during the COVID-19 pandemic. Orthopedic surgery has traditionally lagged behind other surgical subspecialities in providing these opportunities.8 With more emphasis placed on competency-based training, there have been advances especially in arthroscopic and spine surgery that have shown promise.9,10 However, trauma-related simulations remain scarce.11

This study sought to design a low-cost distal femoral and proximal tibial skeletal traction simulation specifically for medical students interested in orthopedic surgery. It was hypothesized that after undergoing the simulation training session, the medical students would technically improve their abilities as well as understanding of the procedure.

METHODS

Simulation model

The simulation model was created using readily available materials shown in figure 1. First, a plaster mold of a human knee was created and bivalved in the sagittal plane. Then femur and tibia Sawbones® (Vashon Island, WA, USA) were positioned to form a knee joint, held in place using spinal needles, and a commercially available silicone product was used to fill the mold (figure 2). Finally, a stockinette sleeve was applied over the top, which allowed for drawing of anatomic landmarks (figure 3). Sawbones® were reused provided the distal femoral or proximal tibial metaphyses remained intact. Repeat testing was performed on the same Sawbones™ for each student.

Knowledge testing

Study participants were recruited from the study institution’s “Orthopedic Bootcamp”, which is a training course for third year students prior to formal audition rotations, as well as other orthopedic-interested medical students. No participant had received training or performed skeletal traction prior to this study. Participants were given a pre-test including three questions administered through Qualtrics™ (Provo, UT, USA) as follows:

  1. Describe the laterality of the start point for distal femoral and proximal tibial traction pin placement.

  2. Describe the appropriate start point for distal femoral and proximal tibial traction pin placement.

  3. Describe the steps for preparing and applying a Steinmann pin for skeletal traction.

Answers were free text, and participants were given 0.5 points for being correct for the femur or tibia in question one and two. Question three was given 1 point if the answer included discussion of correct positioning, sterile technique, use of anesthetic, incision, and bicortical drilling of the pin. A 15-minute overview of indications, safe techniques and practical tips for the application of skeletal traction in the setting of orthopedic trauma was given to the participants in a group setting. Demonstration was then completed for the students utilizing the model. Verbalization of steps including identification of anatomic landmarks and choice of pin placement site, standard preparation, proper application of local anesthetic, creation of an entry point incision, soft tissue dissection, drilling of the pin, and creation of an exit site incision was performed. Emphasis was made on identification of safe landmarks. A post-test was administered with identical questions to the pre-test.

Procedural testing

Each participant was assigned a femur or tibia model. Each student’s Sawbones® model was pre-marked with an “ideal” entry and exit site of a traction pin with safe anatomic placement, central sagittal alignment, and coronal position parallel to the joint line. The participants were allowed to view these sites prior to placement of the Sawbones® into the model. Participants were then asked to identify and palpate the appropriate landmarks on the model, verbalize the appropriate steps for the procedure, and then place a 3.5mm Steinmann pin utilizing a power drill through the model. They were given three attempts, and all were recorded. After each attempt, the bone was removed and examined by the assessor to provide real time feedback. The presence of bicortical and extraarticular pin placement were recorded. Improvement through the three trials was measured based on the distance measured from the center of the student’s entry and exit sites and that of the “ideal” pin. The difference between the angle of the pin and the angle of the joint line was also measured with a manual goniometer.

Our study was deemed exempt by our institution’s Institutional Review Board (IRB). Statistical analysis was performed using an ANOVA test in Microsoft Excel [(Microsoft Corporation. (2021). Microsoft Excel (Version 16.0)]. Significance was set at P<0.05.

A bone and other items on a sheet Description automatically generated with medium confidence
Figure 1.Simulation model supplies (top supplies from left to right, 3-inch plaster rolls, silicone rubber, 10 blade scalpel, 20 gauge spinal needles, 10 Sawbones® femur and tibia; bottom supplies from left to right, stockinette, tape).
A close up of a bone Description automatically generated
Figure 2.Simulation model knee joint with plaster bivalved in the sagittal plane.
A sock with a drawing on it Description automatically generated
Figure 3.Simulation model knee joint (top of picture is towards the head), with anatomic landmarks (palpable joint line, tibial tubercle, adductor tubercle) drawn out on stockinette sleeve.

RESULTS

There were twenty-one total participants who performed the simulation on 20 tibias and 5 femurs. 11 students were in their second year of medical school, three students were in their third year, and seven students were in their fourth year. The cost of supplies to create the model is demonstrated in table 1. The total cost of the supplies for the model was $123.25 (table 1). The mean score on the pre-test was 0.3 out of 3 and the mean score on the post-test was 2.55 out of 3 (P<0.001). In the tibia simulation, the distance from the ideal entry and exit points improved from 0.95 and 1.16 cm to 0.45 and 0.65 cm, respectively (table 2). There were no differences in mean angle from the joint line or number of bicortical or extra-articular pins. In the femur group, there were no differences in ideal entry and exit points, mean angle from the joint line, or number of bicortical or extra-articular pins (table 3). By their third attempt, all participants were able to verbalize the steps to set up and safely place distal femoral or proximal tibial traction pins, identify anatomic landmarks and structures at risk for safe pin placement, and place a bicortical distal femoral or proximal tibial traction pin on the simulation model without violating the joint surface.

Table 1.Supply cost in United States Dollars (USD)
Item and quantity Cost
Silicone rubber x 4 pints 74
3-inch plaster x 4 rolls 15
Femur and tibia sawbones (1 each) 34.25
Total Cost 123.25
Table 2.Tibia simulation data (N = 20)
Attempt number P value
1st 2nd 3rd
Mean distance from ideal entry point (cm) 0.95 0.6575 0.4525 0.009
Mean distance from ideal exit point (cm) 1.155 0.815 0.65 0.010
Mean angle from joint line (degrees) 4.4 4.575 4.05 0.839
Number of bicortical pins 19 19 20 0.813
Number of extra-articular pins 20 20 20 1.0
Table 3.Femur simulation data (N = 5)
Attempt number P value
1st 2nd 3rd
Mean distance from ideal entry point (cm) 0.94 0.52 0.34 0.064
Mean distance from ideal exit point (cm) 0.96 1.12 0.82 0.826
Mean angle from joint line (degrees) 6.6 5.5 7.0 0.843
Number of bicortical pins 5 4 5 0.397
Number of extra-articular pins 5 5 5 1.0

DISCUSSION

Distal femoral and proximal tibial skeletal traction pin placement are common procedures required of junior orthopedic surgery residents taking trauma call. However, the procedure has been shown to be anxiety-inducing as it is not without risks, which can be attributed to technical errors that cause infection and/or neurovascular injury.5,6 There are limited opportunities to practice this skill prior to performing the procedure in-vivo, and a risk-free simulation experience may be beneficial to a new trainee to develop proficiency without risking patient safety.

Low-cost simulation models have been explored in orthopedics and other surgical subspecialities.12–15 In fact, Nielsen et al. recently implemented an educational module for skeletal traction placement, however, it was designed for postgraduate level two orthopedic surgery residents and did not measure data on their actual technical skills.4 Lopez et al. previously utilized a low-cost method for developing a series of tasks to improve skills commonly used by orthopedic surgeons, including the three-dimensional drill accuracy and drill-by-feel accuracy needed to perform skeletal traction pin placement.12 Other simulation studies have worked to improve these skills, but to our knowledge there is not a published low-cost model for teaching accuracy in skeletal traction pin placement.13,14

This study designed a practical teaching session for skeletal traction pin placement with the addition of testing the simulation’s efficacy on a group of orthopedic-interested medical students with no prior experience. Furthermore, this study recorded objective data that showed both an improvement in their understanding of the procedure as well as their technical performance. Offering this experience to learners early in training may improve patient care, as the ability to perform the procedure in a technically correct and safe manner may protect against complications. Secondly, it has already been shown to reduce resident anxiety about performing the procedure.4 The authors believe that this simulation model could successfully be integrated not only into courses for medical students, but also into orthopedic postgraduate level one “bootcamp” experiences prior to starting residency.

Our study is not without limitations. There was a relatively low number of students who performed the distal femoral traction pin simulation owing in part to supply constraints at the time of testing. No model can perfectly replicate human anatomy, but the authors feel this experience offers an excellent opportunity to focus on the technical aspects of the procedure that can be easily replicated on an actual patient. Future models may wish to explore more realistic “skin” instead of a stockinette, or perhaps use fluoroscopy to determine acceptable pin placement.

CONCLUSION

Our low-cost simulation model and short course module improved learners’ understanding of traction pin placement as well as improved their technical procedural performance. This simulation is reproducible and can be implemented in a variety of settings to benefit both orthopedic trainees as well as their future patients.